You can only work with people that you like. And I am not talking about professionalism; I am talking about affection. I am talking about a client and you sharing some common ground.
The most important criterion for the selection of a web designer is likability. Not professionalism, punctuality, skills, talent, or reputation; there are plenty of designers who live up to those standards. Choose a designer whose work appeals to you instinctively. Building a website is a collaboration between you and a designer, and the quality of this relationship will reflect in the final product. Here are some more specific suggestions to guide you in the initial stages of selecting a web designer:
Work with a small team
Small businesses and small design agencies are an ideal match, because collaborations that are as tightly-knit as possible produce the best ideas. Big agencies will not take the time and care to interpret your quirks. Small design agencies, on the other hand, establish a direct line of communication with your business and develop your quirks into a unique web presence. That uniqueness will determine whether your business stands out, or gets lost among thousands of good-enough websites.
Look for skills, not experience
Like the Lichen Spider who blends into tree bark, or the Righteye Flounder who dissolves into the marbled seabed, web designers are versatile creatures. They have a foundation of creative and technical skills that allow them to develop a wide range of styles. The types of industries and styles represented in a designer’s portfolio do not reflect a finite set of capabilities. Rather, a versatile portfolio that is consistent in quality indicates that the designer can tackle any project.
When Milton Glaser talks about common ground, he implies that clients must trust designers at every stage of development. Hiring a web designer is saying: I trust this professional to do something that I can’t do myself. It means giving up a little bit of control. A productive relationship between client and designer is not a one-way channel of communication, but a collaborative process.